This invention relates to systems for the human entry of information, especially by finger touch, into information processing devices. U.S. Pat. No. 3,903,502, assigned to the assignee of this application, discloses a system wherein the user enters information by the act of tracing paths over a cell or cells, and each path possesses certain characteristics, namely, the beginning and/or end points (or termini) specific to the information being entered. These characteristics are used to encode characters (numerical and/or alphabetical).
Other systems exist, and other proposals for systems have been made, to permit a large reduction in the space which conventional keyboards require for information entry. All, however, suffer from defects of practicality. Miniature keyboards, too small for fingertip operation, and a special stylus, are inconvenient and unnatural in use and become inoperable when the stylus is lost. They tend also to be delicate and expensive. Directionally sensitive multiple-function keys are inconvenient and unnatural as well. Multiple keystroke entry methods are especially cumbersome and unreliable for the entry of numerical data. In general, as the space required for these systems diminishes, so also do their naturalness and reliability.
Other information entry systems using scribing-sensing methods, are shown in U.S. Pat. Nos. 3,108,254 (Dimond) and 3,142,039 (Irland et al), or manually interrupting optical paths as in Burkhart 3,234,512.
Thus, although there has been substantial activity in this field, there still exists the need for an information entry system that demands so little space as to permit the successful development of such devices as wristwatch size electronic calculators with an inexpensive, yet natural and reliable information entry system.